Elymuscurvatus grows in moist or damp soils of open forests, thickets, grasslands, ditches, and disturbed ground, especially on bottomland. It is widespread from British Columbia and Washington, through the Intermountain region and northern Rockies, to the northern Great Plains. It is infrequent or rare in the midwest, the Great Lakes region, and the northeast, and is virtually unknown in the southeast. It is similar to Elymusvirginicus , and has sometimes been included in that species as E.virginicus var. submuticus Hook. , but it is more distinct than the varieties of E.virginicus treated above. Although E.virginicus and E.curvatus overlap greatly in range, E.curvatus usually has a distinct growth form, and its anthesis is 1-2 weeks later (Brooks 1974). Its spikes range from being completely exserted, especially west of the Great Plains, to largely sheathed, especially east of the Mississippi River and in more stressed environments. This geographic trend parallels that within E.virginicus, but sheathed plants of E.curvatus can usually be distinguished by their short awns. Clear transitions to E.virginicus, usually var. jejunus , are rare, but, especially from Missouri to Wisconsin, there are occasional plants with 5-10 mm awns on a few lemmas, especially at the spike tips. Rarely, plants from Missouri and Iowa to Quebec have hispid to hirsute spikelets, suggesting introgression with E.virginicus var. intermedius . There are few records of apparent hybrids with other species.